In order to transmit a transmission signal and to receive a receiver signal through the common antenna, a transmitter/receiver module has a high frequency switch which is coupled with the antenna and which switches the circuit in such a way that a transmitter is coupled with the antenna at the time of transmitting and a receiver is coupled with the antenna at the time of receiving.
For example, Patent Literature 1 discloses a high frequency switch circuit that connects a capacitor in parallel with a transmission line in the switch circuit. According to the high frequency switch circuit of Patent Literature 1, there is an explanation that an isolation of equal to or greater than 35 dB is ensured even in a band where a transmitting frequency band and a receiving frequency band partially overlap with each other.
Patent Literature 2 discloses a high frequency switch using an SPST (Single Pole, Single Throw) switch. The high frequency switch of Patent Literature 2 couples in a cascade manner a variable phase shifter that is capable of setting 0 degree or a phase difference of ±90 degrees in a 90-degree hybrid coupler relative to the SPST switch. The 90-degree hybrid coupler is coupled with an output terminal of the variable phase shifter. The phase level at the variable phase shifter is controlled in accordance with the on/off state of the SPST switch, thereby causing a high frequency signal input from an input terminal 1 to be output through either one of an output terminal 2 and an output terminal 3.
It is conventionally well-known that, as a typical circuit configuration, anti-parallel diodes are utilized as a limiter circuit (see, for example, Patent Literature 3 or 4). Moreover, Patent Literature 5 discloses the use of a limiter diode as a switching element.